Biological information analysis device, system, and program

ABSTRACT

A biological information analysis device includes: an indicator extraction unit configured to extract, from time-series data regarding blood pressure waveforms consecutively measured by a sensor that is configured to be worn on a body part of a user and to be capable of non-invasively measuring a blood pressure waveform for each heartbeat, and from time-series data regarding breathing measured by a respiration sensor during a period of time corresponding to the time-series data regarding blood pressure waveforms, an indicator indicating the relationship between the user&#39;s breathing and changes in blood pressure; and a processing unit configured to perform processing that is based on the indicator thus extracted.

TECHNICAL FIELD

The present invention relates to technology for acquiring usefulinformation from a blood pressure waveform that has been measured.

RELATED ART

There is a known technology for measuring changes in the internalpressure of a radial artery and recording the shape of a pressure pulsewave (blood pressure waveform). Patent Document 1 (JP 2008-61824Mdiscloses that a blood pressure waveform is measured using a tonometrymethod, and pieces of information such as an AI (Augmentation Index)value, a pulse wave period, a baseline fluctuation rate, sharpness, andan ET (Ejection Time) are acquired from the blood pressure waveform.Also, Patent Document 2 (JP 2005-532111A) discloses that a bloodpressure waveform is measured using a wristwatch-type blood pressuremeter, in which a mean arterial pressure, a mean systolic pressure, amean diastolic pressure, a mean systolic pressure indicator, and a meandiastolic pressure indicator are calculated from the blood pressurewaveform, and an alert is output when any of these values deviates froma reference value.

RELATED ART DOCUMENTS Patent Documents

-   Patent Document 1: JP 2008-61824A-   Patent Document 2: JP 2005-532111A

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

It is known that blood pressure can be controlled by using a breathingtechnique. However, it is envisioned that the amount of change in bloodpressure varies for each person due to the influence of thecharacteristics and the disease state of each person, even if the samebreathing pattern is used. Therefore, a standard routine for improvementin breathing does not have a sufficient blood pressure control effect.Also, for example, when a user experiences an increase in blood pressureor poor physical condition, even if the user knows that blood pressurecan be controlled by using a breathing technique, the user does not knowwhat specific measures can be taken.

The inventors of the present invention have worked hard to develop ablood pressure measurement device that can accurately measure anambulatory blood pressure waveform for each heartbeat, and to put such adevice into practical use. Through experiments performed on subjectsduring the development phase, the inventors have found that it can bepossible to quantitatively evaluate a relationship between breathing andchanges in blood pressure by accurately and non-invasively monitoringambulatory blood pressure waveforms for each heartbeat.

Therefore, the present invention aims to provide a novel technology foracquiring information regarding a relationship between breathing andchanges in blood pressure.

Means for Solving the Problems

To achieve the above-described aim, the present invention employs thefollowing configurations.

A biological information analysis device according to the presentinvention is a biological information analysis device that includes: anindicator extraction unit configured to extract, from time-series dataregarding blood pressure waveforms consecutively measured by a sensorthat is configured to be worn on a body part of a user and to be capableof non-invasively measuring a blood pressure waveform for eachheartbeat, and from time-series data regarding breathing measured by arespiration sensor during a period of time corresponding to thetime-series data regarding blood pressure waveforms, an indicatorindicating a relationship between the user's breathing and changes inblood pressure; and a processing unit configured to perform processingthat is based on the indicator thus extracted.

With the configuration according to the present invention, analysis isperformed using time-series data regarding blood pressure waveformsmeasured from each heartbeat of the user, and time-series data regardingbreathing measured during a period corresponding thereto. Therefore, itis possible to quantitatively analyze a relationship (a cause-effectrelationship or a correlation) between breathing and change in bloodpressure, which is a characteristic that is unique to the user.

It is preferable that the indicator extraction unit is configured tospecify a plurality of periods of time that have the same breathingpattern, from the time-series data regarding breathing, and extract anindicator indicating the relationship between breathing and changes inblood pressure for the breathing pattern, from pieces of data regardingblood pressure waveforms respectively corresponding to the plurality ofperiods of time. By analyzing pieces of data regarding blood pressurewaveforms corresponding to periods of time that have the same breathingpattern, it is possible to improve the reliability and objectivity ofthe indicator. For example, it is preferable that the indicatorextraction unit is configured to extract, as the indicator, a trend inchanges in blood pressure and/or the amount of changes that is/arecommon to pieces of data regarding blood pressure waveforms.

It is also preferable that the indicator extraction unit is configuredto classify ways the user breathes, into a plurality of breathingpatterns, based on the time-series data regarding the user's breathing.By classifying the user's breathing into a plurality of breathingpatterns based on time-series data regarding the user's breathing, it ispossible to acquire breathing patterns that are suitable for the user'scharacteristics.

For example, it is preferable that the time-series data regardingbreathing includes, for each of a plurality of periods of time thatinclude an exhalation period and an inhalation period, the length of theperiod of time and/or the amount of breath. If this is the case, theindicator extraction unit is configured to classify the plurality ofperiods of time into a plurality of breathing patterns based on thelength of the period of time and/or the amount of breath. This isbecause the influence on blood pressure varies depending on the lengthof time spent for exhaling and inhaling and the amount of breath that isexhaled and inhaled.

It is preferable that the indicator extraction unit is configured toextract an indicator indicating the relationship between breathing andchanges in blood pressure for each of the plurality of breathingpatterns. By identifying the relationship between breathing and changesin blood pressure for each of the plurality of breathing patterns, it ispossible to acquire information that is very useful for knowingcharacteristics of the user's respiratory and circulatory organs.

For example, it is preferable that the processing unit is configured toperform processing to output information representing the relationshipbetween the user's breathing and changes in blood pressure, based on theindicator. Because such information is provided, the user can understandthe relationship between his/her breathing and changes in bloodpressure, and recognize an effective way of breathing when regulatingblood pressure.

It is also preferable that the indicator extraction unit is configuredto generate, for each of the plurality of breathing patterns, arelationship table that defines an indicator indicating the relationshipbetween breathing and changes in blood pressure, and the processing unitis configured to select a breathing pattern that is to be followed inorder to achieve a desired change in blood pressure, based on therelationship table, and recommend the selected breathing pattern to theuser. With this configuration, it is possible to suggest an appropriatebreathing pattern according to the user's characteristics and aim.Therefore, the user can effectively control his/her blood pressure byusing a breathing technique.

It is preferable that the indicator extraction unit includes, as changesin blood pressure, at least one of: changes in systolic blood pressure;changes in diastolic blood pressure; changes in an AI (AugmentationIndex); changes in the number of times a surge in blood pressure occurs;and changes in the amount of an increase in a surge in blood pressure.

Note that the present invention can be interpreted as a biologicalinformation analysis device or system that is provided with at least oneof the above-described configurations or at least one of theabove-described functions. The present invention can also be interpretedas a biological information analysis method that includes at least partof the above-described processing, or a program that causes a computerto execute such a method, or a computer-readable recording medium onwhich such a program is recorded in a non-transitory manner. The presentinvention can be formed by combining the above-described configurationsand the above-described kinds of processing with each other unless notechnical inconsistency occurs.

EFFECTS OF THE INVENTION

According to the present invention, it is possible to provide a noveltechnology for acquiring information regarding a relationship betweenbreathing and changes in blood pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic external configuration of a biologicalinformation analysis system 10.

FIG. 2 is a block diagram showing a hardware configuration of thebiological information analysis system 10.

FIG. 3 is a cross-sectional view schematically showing a configurationof a blood pressure measurement unit 20 and a state in which measurementis performed.

FIG. 4 shows a blood pressure waveform that is measured by the bloodpressure measurement unit 20.

FIG. 5 is a block diagram illustrating processing that is performed by abiological information analysis device 1.

FIG. 6 shows a waveform (a blood pressure waveform) of a pressure pulsewave from a radial artery corresponding to one heartbeat.

FIG. 7 is a flowchart for processing that is performed to represent arelationship between breathing and changes in blood pressure as anindicator according to Example 1.

FIG. 8 is a diagram illustrating analysis of the relationship betweenbreathing and changes in blood pressure according to Example 1.

FIGS. 9A and 9B are diagrams showing an example of a relationship tablethat shows the relationship between breathing and changes in bloodpressure according to Example 1.

EMBODIMENTS OF THE INVENTION

The following describes a preferred embodiment of the present inventionwith reference to the drawings. Note that the following descriptions ofcomponents may be modified as appropriate depending on the configurationof a device to which the present invention is applied, and on variousconditions, and the scope of the present invention is not intended to belimited to the following descriptions.

Biological Information Analysis System

FIG. 1 shows a schematic external configuration of a biologicalinformation analysis system 10 according to an embodiment of the presentinvention. FIG. 1 shows a state in which the biological informationanalysis system 10 is worn on the left wrist. The biological informationanalysis system 10 includes a main body 11 and a belt 12 that is fixedto the main body 11. The biological information analysis system 10 is aso-called wearable device, and is worn such that the main body 11 is incontact with the skin on the palm side of the wrist, and the main body11 is located over a radial artery TD that lies beneath the skin.Although the device is configured to be worn on the radial artery TD inthe present embodiment, the device may be configured to be worn onanother superficial artery.

FIG. 2 is a block diagram showing a hardware configuration of thebiological information analysis system 10. In general, the biologicalinformation analysis system 10 includes a measurement unit 2 and thebiological information analysis device 1. The measurement unit 2 is adevice that performs measurement to acquire information that is used toanalyze biological information, and includes a blood pressuremeasurement unit 20, a body movement measurement unit 21, an environmentmeasurement unit 22, and a respiration measurement unit 28. However,note that the configuration of the measurement unit 2 is not limited tothat shown in FIG. 2. For example, a unit that measures biologicalinformation other than blood pressure or a body movement (e.g. bodytemperature, blood-sugar level, or brain waves) may be added. Also, anyunit that is not used in the example described below is not an essentialcomponent, and may be omitted from the biological information analysissystem 10. The biological information analysis device 1 is a device thatanalyzes biological information based on information acquired from themeasurement unit 2, and includes a control unit 23, an input unit 24, anoutput unit 25, a communication unit 26, and a storage unit 27. Theunits 20 to 27 are connected to each other so that signals can beexchanged between them via a local bus or other signal lines. Thebiological information analysis system 10 also includes a power supply(a battery), which is not shown.

The blood pressure measurement unit 20 measures a pressure pulse wavefrom the radial artery TD by using a tonometry method. The tonometrymethod is for forming a flat area in the artery TD by pressing theartery from the skin with appropriate pressure, adjusting the balancebetween the internal pressure and the external pressure of the artery,and non-invasively measuring the pressure pulse wave using a pressuresensor.

The body movement measurement unit 21 includes a tri-axis accelerationsensor, and measures the movement of the user's body (body movement)using this sensor. The body movement measurement unit 21 may include acircuit that converts the format of an output from the tri-axisacceleration sensor into a format that is readable to the control unit23.

The environment measurement unit 22 measures environmental informationthat may affect mental and physical conditions of the user (inparticular the blood pressure). The environment measurement unit 22 mayinclude, for example, an atmospheric temperature sensor, a humiditysensor, an illuminance sensor, an altitude sensor, a position sensor,and so on. The environment measurement unit 22 may include a circuitthat converts the format of outputs from these sensors and so on into aformat that is readable to the control unit 23.

The respiration measurement unit 28 is a unit that measures the state ofthe user's breathing. The respiration measurement unit 28 may include,for example, a respiration sensor such as a flow sensor. The respirationmeasurement unit 28 can at least discern between exhalation andinhalation, and measure the duration of exhalation and the duration ofinhalation, and preferably, it can also measure the amount of breath.The respiration measurement unit 28 may include a circuit that convertsthe format of outputs from the respiration sensor and so on into aformat that is readable to the control unit 23.

The control unit 23 performs various kinds of processing, such ascontrolling each unit of the biological information analysis system 10,acquiring data from the measurement unit 2, storing the acquired data inthe recording unit 27, processing and analyzing data, and inputting andoutputting data. The control unit 23 includes a hardware processor(hereinafter referred to as the “CPU”) a ROM (Read Only Memory), a RAM(Random Access Memory), and so on. Processing that is performed by thecontrol unit 23, which will be described later, is realized by the CPUreading and executing a program stored in the ROM or the storage unit27. The RAM functions as a work memory that is used by the control unit23 when performing various kinds of processing. Although acquisition ofdata from the measurement unit 2 and the storing of data in the storageunit 27 are performed by the control unit 23 in the present embodiment,it is possible to employ a configuration in which the measurement unit 2directly stores (writes) data in the storage unit 27.

Each of the constituent components of the embodiment such as ameasurement unit, an indicator extraction unit, a processing unit, adetermination unit, a risk database, an input unit, an output unit, acase database, and so on may be implemented as pieces of hardware in thebiological information analysis system 10. The indicator extractionunit, the processing unit, and the determination unit may receive anexecutable program stored in the storage unit 27, and execute theprogram. The indicator extraction unit, the processing unit, and thedetermination unit may receive data from the blood pressure measurementunit 20, the body movement measurement unit 21, the environmentmeasurement unit 22, the input unit 24, the output unit 25, thecommunication unit 26, the storage unit 27, and so on as required.Databases such as the risk database and the case database may beimplemented using the storage unit 27 and so on, and store pieces ofinformation that are arranged such that a data search and dataaccumulation can be easily performed. Here, for example, theconfiguration, operations, and so on of the biological informationanalysis system 10 are disclosed in JP 2016-082069A. The contents ofthis disclosure are incorporated herein by reference. Also, theconfiguration, operations, and so on of the blood pressure measurementunit are disclosed in JP 2016-087003A. The contents of this disclosureare incorporated herein by reference.

The input unit 24 provides an operation interface for the user. Forexample, an operation button, a switch, a touch panel, and so on may beused.

The output unit 25 provides an interface that outputs information to theuser. For example, a display device (such as a liquid crystal display)that outputs information using images, an audio output device or abeeper that outputs information using audio, an LED that outputsinformation by blinking, a vibration device that outputs information byvibrating, and so on may be used.

The communication unit 26 performs data communication with anotherdevice. Any data communication method such as a wireless LAN orBluetooth (registered trademark) may be used.

The storage unit 27 is a storage medium that can store data and fromwhich data can be read out, and stores programs that are to be executedby the control unit 23, pieces of measurement data acquired from themeasurement units, and various kinds of data acquired by processing thepieces of measurement data, and so on. The storage unit 27 is a mediumthat accumulates pieces of information that are to be stored, through anelectrical, magnetic, optical, mechanical, or chemical action. Forexample, a flash memory is used. The storage unit 27 may be a portableunit such as a memory card, or built into the biological informationanalysis system 10.

At least one unit or all units out of the body movement measurement unit21, environment measurement unit 22, the control unit 23, the input unit24, the output unit 25, and the storage unit 27 may be configured as adevice that is separate from the main body 11. That is, as long as theblood pressure measurement unit 20 and the main body 11 thatincorporates a circuit that controls the blood pressure measurement unit20 are configured to be wearable on a wrist, the configurations of otherunits can be freely designed. If this is the case, the main body 11cooperates with another unit via the communication unit 26. Variousconfigurations can be conceived of. For example, the functions of thecontrol unit 23, the input unit 24, and the output unit 25 may berealized using a smartphone application, and required data may beacquired from an activity monitor that has the functions of the bodymovement measurement unit 21 and the environment measurement unit 22.Also, a sensor that measures biological information other than bloodpressure may be provided. For example, a sleep sensor, a pulse oximeter(SpO2 sensor), a blood-sugar level sensor, and the like may be combined.

Although the sensor (the blood pressure measurement unit 20) thatmeasures blood pressure and the component (including the control unit 23and so on) that performs processing to analyze blood pressure waveformdata are provided in one device in the present embodiment, they may beprovided in separate members. In the present embodiment, the component(including the control unit 23 and so on) that performs processing toanalyze biological information is referred to as a biologicalinformation analysis device, and the device that includes thecombination of the measurement unit and the biological informationanalysis device is referred to as a biological information analysissystem. However, these names are given for descriptive purposes, and themeasurement unit and the component that performs processing to analyzebiological information may be referred to as a biological informationanalysis device as a whole, or other names may be used.

Measurement of Blood Pressure Waveform

FIG. 3 is a cross-sectional view schematically showing the configurationof the blood pressure measurement unit 20 and a state in whichmeasurement is performed. The blood pressure measurement unit 20includes a pressure sensor 30 and a pressurizing mechanism 31 forpressing the pressure sensor 30 against a wrist. The pressure sensor 30includes a plurality of pressure detection elements 300. The pressuredetection elements 300 detect pressure and convert the pressure into anelectrical signal. For example, elements that utilize a piezoresistiveeffect may be preferably used. The pressurizing mechanism 31 includes,for example, an air bag and a pump that adjusts the internal pressure ofthe air bag. As a result of the control unit 23 controlling the pump toincrease the internal pressure of the air bag, the air bag expands andthe pressure sensor 30 is pressed against the surface of the skin. Notethat the pressurizing mechanism 31 may be any mechanism as long as itcan adjust the pressing force of the pressure sensor 30 applied to thesurface of the skin, and is not limited to a mechanism that uses an airbag.

Upon the biological information analysis system 10 being worn on a wristand activated, the control unit 23 controls the pressurizing mechanism31 of the blood pressure measurement unit 20 to keep the pressing forceof the pressure sensor 30 in an appropriate state (a tonometry state).Then, pressure signals detected by the pressure sensor 30 aresequentially acquired by the control unit 23. Pressure signals acquiredfrom the pressure sensor 30 are generated by digitizing analoguephysical amounts (e.g. voltage values) output by the pressure detectionelements 300, through an A/D converter circuit or the like that employsa well-known technology. Preferable analogue values such as currentvalues or resistance values may be employed as the analogue physicalamounts, depending on the type of the pressure detection elements 300.Signal processing such as the aforementioned A/D conversion may beperformed using a predetermined circuit provided in the blood pressuremeasurement unit 20, or performed by another unit (not shown) providedbetween the blood pressure measurement unit 20 and the control unit 23.Each pressure signal acquired by the control unit 23 corresponds to aninstantaneous value of the internal pressure of the radial artery TD.Therefore, it is possible to acquire time-series data regarding bloodpressure waveforms by acquiring pressure signals with time granularityand continuity that make it possible to ascertain a blood pressurewaveform for each heartbeat. The control unit 23 stores the pressuresignals sequentially acquired from the pressure sensor 30, in thestorage unit 27, together with information regarding points in time atwhich the pressure signals were measured. The control unit 23 may storethe acquired pressure signals in the storage unit 27 without change, orstore the pressure signals in the storage unit 27 after performingrequired signal processing on the pressure signals. Required signalprocessing includes, for example, processing that is performed tocalibrate each pressure signal such that the amplitude of the pressuresignal matches the blood pressure value (e.g. the brachial bloodpressure), processing that is performed to reduce or remove noise ineach pressure signal, and so on.

FIG. 4 shows a blood pressure waveform measured by the blood pressuremeasurement unit 20. The horizontal axis indicates time and the verticalaxis indicates blood pressure. Although the sampling frequency may beset to any value, it is preferably set to be no less than 100 Hz so thatcharacteristics of the shape of a waveform corresponding to oneheartbeat can be reproduced. Typically, the period of one heartbeat isapproximately one second, and therefore approximately one hundred ormore data points can be acquired on a waveform corresponding to oneheartbeat.

The blood pressure measurement unit 20 according to the presentembodiment is advantageous in terms of the following.

The blood pressure measurement unit 20 can measure a blood pressurewaveform for each heartbeat. As a result, it is possible to acquirevarious indicators related to blood pressure, the state of the heart,cardiovascular risks, and so on, based on the characteristics of theshape of the blood pressure waveform. In addition, it is possible tomonitor for instantaneous values of blood pressure. Therefore, it ispossible to instantaneously detect a blood pressure surge (a sudden risein the blood pressure value), and to detect changes in blood pressureand irregularities in a blood pressure waveform that may occur in a veryshort period of time (corresponding to one to several heartbeats)without missing them.

As a portable blood pressure meter, a blood pressure meter that is to beworn on a wrist or an upper arm and employs an oscillometric method tomeasure blood pressure has come into practical use. However, aconventional portable blood pressure meter can only measure the meanvalue of blood pressure based on changes in the internal pressure of acuff during a period of several seconds to a dozen or so secondscorresponding to a plurality of heartbeats, and cannot acquiretime-series data regarding a blood pressure waveform for each heartbeat,unlike the blood pressure measurement unit 20 according to the presentembodiment.

The blood pressure measurement unit 20 can record time-series dataregarding blood pressure waveforms. By acquiring time-series dataregarding blood pressure waveforms, and, for example, discerningcharacteristics of the blood pressure waveform related to temporalchanges, or performing a frequency analysis on the time-series data toextract a specific frequency component, it is possible to acquirevarious indicators related to blood pressure, the state of the heart,cardiovascular risks, and so on.

The device employs a portable (wearable) type configuration, and lessburden is placed on the user during measurement. Therefore, continuousmeasurement for a long time, and even 24-hour blood pressure monitoring,can be relatively easily performed. Also, since the device is of aportable type, changes in not only blood pressure under restingconditions, but also an ambulatory blood pressure (for example, duringdaily life or exercise) can be measured. As a result, it is possible tograsp how blood pressure is affected by behaviours in daily life (suchas sleeping, eating, commuting, working, and taking medicine) andexercise, for example.

Conventional products are types of devices that measure blood pressureunder resting conditions, with an arm or a wrist fixed to a bloodpressure measurement unit, and cannot measure changes in blood pressurein daily life or during exercise, unlike the biological informationanalysis system 10 according to the present embodiment.

The blood pressure measurement unit 20 can be easily combined or linkedwith other sensors. For example, it is possible to make an evaluation ofa cause-effect relationship or a composite evaluation with informationthat can be acquired by other sensors (e.g. a body movement,environmental information such as an atmospheric temperature, biologicalinformation such as SpO2 and respiration information).

Biological Information Analysis Device

FIG. 5 is a block diagram illustrating processing that is performed bythe biological information analysis device 1. As shown in FIG. 5, thebiological information analysis device 1 includes an indicatorextraction unit 50 and a processing unit 51. In the present embodiment,processing performed by the indicator extraction unit 50 and theprocessing unit 51 may be realized by the control unit 23 executing aprogram that is required for the processing. The program may be storedin the storage unit 27. When the control unit 23 executes the requiredprogram, the subject program stored in the ROM or storage unit 27 isloaded to the RAM. Then, the control unit 23 interprets and executes theprogram loaded to the RAM, using the CPU, to control each constituentcomponent. Note that at least one or all of the processing proceduresexecuted by the indicator extraction unit 50 and the processing unit 51may be realized using a circuit such as an ASIC or an FPGA.Alternatively, at least one or all of the processing procedures executedby the indicator extraction unit 50 and the processing unit 51 may berealized using a computer (e.g. a smartphone, a tablet terminal, apersonal computer, or a cloud server) that is separate from the mainbody 11.

The indicator extraction unit 50 acquires time-series data regardingblood pressure waveforms, which have been consecutively measured by theblood pressure measurement unit 20, from the storage unit 27. Theindicator extraction unit 50 extracts, from the acquired time-seriesdata regarding blood pressure waveforms, indicators that are related tocharacteristics of the blood pressure waveforms. Here, characteristicsof a blood pressure waveform include, for example, characteristics ofthe shape of a blood pressure waveform corresponding to one heartbeat,temporal changes in a blood pressure waveform, and frequency componentsof a blood pressure waveform. However, characteristics of a bloodpressure waveform are not limited to those listed above. The extractedindicators are output to the processing unit 51. There are variouscharacteristics and indicators regarding a blood pressure waveform, andthe characteristics and indicators that are to be extracted may bedesigned or selected as appropriate according to the purpose ofprocessing that is to be performed by the processing unit 51.Characteristics and indicators that can be extracted from measurementdata regarding blood pressure waveforms according to the presentembodiment will be described later in detail.

When obtaining indicators, the indicator extraction unit 50 may usemeasurement data that has been acquired by the body movement measurementunit 21 and/or measurement data that has been acquired by theenvironment measurement unit 22, in addition to measurement dataregarding blood pressure waveforms. Also, although not shown in thedrawings, pieces of measurement data that have been acquired by a sleepsensor, an SpO2 sensor, a blood-sugar level sensor, and the like may becombined with one another. By performing complex analysis on a pluralityof kinds of measurement data acquired by a plurality of sensors, it ispossible to perform more advanced information analysis of a bloodpressure waveform. For example, it is possible to classify pieces ofdata regarding blood pressure waveforms according to states of the user,such as a resting state and a moving state, a state when an atmospherictemperature is high and a state when it is low, a light sleep state anda deep sleep state, a breathing state and an apnea state, and so on.Alternatively, it is possible to extract information regarding theinfluence of body movement, an activity amount, activity intensity, achange in an atmospheric temperature, apnea, the user's breathing, etc.on blood pressure, and thus evaluate the cause-effect relationship, thecorrelation, etc. between pieces of measurement data.

The processing unit 51 receives the indicators extracted by theindicator extraction unit 50. The processing unit 51 performs processingthat is based on the received indicators. Various kinds of processingcan be conceived of as processing that is based on the indicators. Forexample, the processing unit 51 may provide the values of the extractedindicators or changes in the values to a user, a doctor, a public healthnurse, or the like to prompt the utilization of the indicators in thefields of health care, treatment, health guidance, and so on.Alternatively, the processing unit 51 may estimate cardiovascular risksfrom the extracted indicators, or provide guidelines for healthmaintenance or risk mitigation. Furthermore, when an increase in therisk of a cardiac disease occurring is detected or predicted based on anindicator, the processing unit 51 may inform the user or his/her doctor,or perform control to prevent the user from performing an action thatburdens his/her heart and so on, or to prevent a cardiovascular eventfrom occurring.

Information Acquired from Blood Pressure Waveform

FIG. 6 shows a waveform (a blood pressure waveform) of a pressure pulsewave from a radial artery corresponding to one heartbeat. The horizontalaxis indicates time t (msec) and the vertical axis indicates bloodpressure BP (mmHg).

A blood pressure waveform is the waveform of a composite waveconstituted by an “ejection wave” that is generated when the heartcontracts and pumps out blood, and a “reflection wave” that is generatedwhen an ejection wave is reflected at a branch point of a peripheralvessel or an artery. The following shows examples of characteristicpoints that can be extracted from a blood pressure waveformcorresponding to one heartbeat.

-   -   A point F1 is the rising point of the pressure pulse wave. The        point F1 corresponds to the ejection start point of the heart,        i.e. the point at which the aortic valve opens.    -   A point F2 is a point at which the amplitude (the pressure) of        the ejection wave is at the maximum (a first peak).    -   A point F3 is an inflection point that appears midway in a drop        in the ejection wave, due to a reflection wave being        superimposed.    -   A point F4 is the minimum point, which appears between the        ejection wave and the reflection wave, and is also referred to        as a notch. This point corresponds to the point at which the        aortic valve closes.    -   A point F5 is the peak of the reflection wave (a second peak),        which appears after the point F4.    -   A point F6 is the end point of one heartbeat, and corresponds to        the ejection start point of the next heartbeat, i.e. the start        point of the next heartbeat.

The indicator extraction unit 50 may use any algorithm to detect theabove-described characteristic points. For example, the indicatorextraction unit 50 may perform computations to obtain an nth orderdifferential waveform of a blood pressure waveform, and detect thezero-crossing points to extract the characteristic points (theinflection points) of the blood pressure waveform (the points F1, F2,F4, F5, and F6 can be detected from the first order differentialwaveform, and the point F3 can be detected from the second orderdifferential waveform or the fourth order differential waveform).Alternatively, the indicator extraction unit 50 may read out, from thestorage unit 27, a waveform pattern on which the characteristic pointshave been arranged in advance, and perform fitting of the waveformpattern to the target blood pressure waveform to specify the respectivepositions of the characteristic points.

The indicator extraction unit 50 performs computations based on time tand pressure BP of each of the above-described characteristic points F1to F6, and can thus obtain various kinds of information (values,characteristic amounts, indicators, etc.) from the blood pressurewaveform of one heartbeat. The following are typical examples ofinformation that can be acquired from a blood pressure waveform. Notethat tx and BPx respectively represent time and blood pressurecorresponding to a characteristic point Fx.

-   -   Pulse Wave Interval (Period of Heartbeat) TA=t6−t1    -   Heart Rate PR=1/TA    -   Pulse Wave Rising Time UT=t2−t1    -   Systole TS=t4−t1    -   Diastole TD=t6−t4    -   Reflection Wave Delay Time=t3−t1    -   Maximum Blood Pressure (Systolic Blood Pressure) SBP=BP2    -   Minimum Blood Pressure (Diastolic Blood Pressure) DBP=BP1    -   Mean Blood Pressure MAP=(Area of Blood Pressure Waveform from t1        to t6)/Period of Heartbeat TA    -   Mean Blood Pressure during Systole=(Area of Blood Pressure        Waveform from t1 to t4)/Systole TS    -   Mean Blood Pressure during Diastole=(Area of Blood Pressure        Waveform from t4 to t6)/Diastole TD    -   Pulse Pressure PP=Maximum Blood Pressure SBP−Minimum Blood        Pressure DBP    -   Late Systolic Pressure SBP2=BP3    -   AI (Augmentation Index)=(Late Systolic Pressure SBP2−Minimum        Blood Pressure DBP)/Pulse Pressure PP

Basic statistics of these pieces of information (values, characteristicamounts, and indicators) can also be used as indicators. Basicstatistics include, for example, representative values (a mean value, amedian value, a mode value, the maximum value, the minimum value, and soon) and the degree of scatter (dispersion, a standard deviation, acoefficient of variation, and so on). Temporal changes in these piecesof information (values, characteristic values, and indicators) can alsobe used as indicators.

In addition, the indicator extraction unit 50 can also acquire anindicator called BRS (Baroreflex Sensitivity) by performing computationson pieces of heartbeat information. This indicator indicates the abilityto regulate blood pressure to be constant. Examples of methods forcalculating the indicator include a spontaneous sequence method. This isa method for only extracting a sequence in which the maximum bloodpressure SBP and the pulse wave interval TA consecutively rise or fallover the period of three or more heartbeats in synchronization with eachother, plotting the maximum blood pressure SBP and the pulse waveinterval TA onto a two-dimensional plane, and defining the inclinationof the regression line obtained through a least squares method as theBRS.

As described above, the use of the biological information analysissystem 10 according to the present embodiment makes it is possible toacquire various kinds of information from blood pressure waveform data.However, the biological information analysis system 10 need notimplement all of the functions that are required to acquire all of thekinds of information described above. The biological informationanalysis system 10 need only implement functions that are required toacquire necessary information, depending on the configuration of thebiological information analysis system 10, who the user is, the purposeof use, the location of use, and so on. Also, each function may beprovided as a program module (a piece of application software), and thebiological information analysis system 10 may employ a mechanism withwhich a function can be added by installing a necessary program moduleon the biological information analysis system 10.

The following illustrates an example, which is a specific application,of the biological information analysis system 10.

EXAMPLE 1

The present example proposes a method for suggesting a breathingtechnique that is suitable for the characteristics and the state ofdisease of each individual user in an objective manner by representingthe relationship between breaths and changes in blood pressure based ontime-series data regarding breathing and blood pressure measured fromusers.

Note that conventional blood pressure meters that employ anoscillometric method cannot accurately keep track of each breathingaction, or the influence of each action of exhaling/inhaling on bloodpressure, because a plurality of breathing actions are performed whileblood pressure is measured once. In contrast, the device according tothe present example can accurately and non-invasively measure a bloodpressure waveform for each heartbeat, and is thus able to quantitativelyanalyze the influence of each action of exhaling/inhaling on bloodpressure or the waveform thereof.

As shown in FIG. 2, the biological information analysis system 10according to the present example includes a respiration sensor thatserves as the respiration measurement unit 28. However, since it is onlynecessary to measure breathing and blood pressure waveforms insynchronization, the biological information analysis system 10 may notbe provided with a respiration measurement unit, and the biologicalinformation analysis system 10 may simply use data measured by anotherrespiration sensor. If this is the case, measurement data regardingblood pressure waveforms and measurement data acquired by therespiration sensor can be associated with each other in terms of time,based on measurement time information (time stamps), for example.

As a respiration sensor, a flow sensor that can detect the direction inwhich air flows, such as that disclosed in JP H10-185639A, can befavorably used. This flow sensor detects an air flow caused by thebreathing action to determine whether the action is exhalation orinhalation. Alternatively, a pressure sensor or a vibration sensor maybe used as a respiration sensor. If this is the case, body movementcaused by the breathing action is detected by a pressure sensor, avibration sensor, or the like that is attached to a body part, and thusthe breathing action is indirectly detected.

FIG. 7 shows an example of a flowchart for processing according to thepresent example. First, in order to grasp the relationship betweenbreathing and changes in blood pressure, the user wears the biologicalinformation analysis system 10 and the respiration sensor, and bloodpressure waveforms and breathing are measured (step 4500). Time-seriesdata regarding blood pressure waveforms and time-series data regardingbreathing are stored in the storage unit 27. The time-series dataregarding breathing includes pieces of information regarding exhalationperiods (periods of time during which air is exhaled) and pieces ofinformation regarding inhalation periods (periods of time during whichair is inhaled), which are arranged one after the other. A piece ofinformation regarding an exhalation period includes the start time andthe end time of the period, the length of the period (also referred toas the duration of exhalation), and the amount of breath in the period(the amount of exhaled air, which is also referred to as an exhaleamount). A piece of information regarding an inhalation period includesthe start time and the end time of the period, the length of the period(also referred to as the duration of inhalation), and the amount ofbreath in the period (the amount of inhaled air, which is also referredto as an inhale amount).

Next, the indicator extraction unit 50 analyzes the relationship betweenbreathing and changes in blood pressure (step 4501). Specifically, theindicator extraction unit 50 reads, from the storage unit 27,time-series data regarding blood pressure waveforms, and time-seriesdata regarding breathing measured in the period corresponding to thetime-series data regarding blood pressure waveforms. Thereafter, asshown in FIG. 8, the indicator extraction unit 50 specifies exhalationperiods and inhalation periods based on the time-series data regardingbreathing, and divides the time-series data regarding blood pressurewaveforms into blood pressure waveforms respectively corresponding tothe periods. Thereafter, the indicator extraction unit 50 performs datamining processing such as cross tabulation or regression analysis onpieces of information regarding breathing respectively corresponding tothe periods, and information regarding blood pressure waveformscorresponding thereto, to extract an indicator indicating therelationship between breathing and changes in blood pressure.

For example, the indicator extraction unit 50 classifies (typifies) theways the user breathes, into a plurality of patterns, based oninformation regarding breathing in each period. The classification intobreathing patterns may be performed based on, for example, the length ofthe period and/or the amount of breath. Here, exhalation periods andinhalation periods may be classified so as to be separate from eachother, or classified into sets each consisting of an exhalation periodand an inhalation period (each set is referred to as a breathingperiod). Thereafter, the indicator extraction unit 50 may collect piecesof data regarding blood pressure waveforms for a plurality of periodsthat have the same breathing pattern, and extract, as indicatorsindicating the relationship between breathing and changes in bloodpressure, a trend in changes in blood pressure (an increase, a decrease,no change, and so on) and/or the amount of changes (the amount of anincrease, the amount of a decrease, and so on) that are/is common to thepieces of data regarding blood pressure waveforms. By performing thesame processing for each breathing pattern, it is possible to obtain anindicator indicating the relationship between breathing and changes inblood pressure for each of a plurality of breathing patterns.

Here, “data regarding blood pressure waveforms corresponding to a givenperiod” may be “data regarding blood pressure waveforms in the givenperiod” or “data regarding blood pressure waveforms of a plurality ofperiods that include the period and one or more periods that areprevious and/or subsequent to the period”. In the former case, changesin blood pressure waveforms within one period (for example, an increaserate and a decrease rate of systolic blood pressure) are items that areto be used to evaluate changes in blood pressure. In the latter case,changes in blood pressure waveforms within a plurality of periods (forexample, the amount of change in systolic blood pressure (SBP), theamount of change in diastolic blood pressure (DBP), the amount of changein AI (Augmentation Index), the amount of change in the number of timesa surge in blood pressure has occurred, and the amount of change in theamount of increase in a surge in blood pressure) are items that are tobe used to evaluate changes in blood pressure. Alternatively, as “dataregarding blood pressure waveforms corresponding to a given period”,“data regarding blood pressure waveforms measured upon a predeterminedperiod of time elapsing after the period” may be used. Such an analysisis effective if the influence of breathing on blood pressure waveformsappears upon a predetermined period of time elapsing.

Next, the indicator extraction unit 50 stores the relationship betweenbreathing and changes in blood pressure (an indicator) acquired in step4501 for each breathing pattern, in the storage unit 27, in the form ofa relationship table (step 4502). FIGS. 9A and 9B show an example of therelationship table. It can be seen from the relationship table shown inFIG. 9A that, if a small amount of air is inhaled in a short period oftime, the SBP decreases by 10 mmHg, and if a large amount of air isinhaled even in a short period of time, the SBP decreases by 30 mmHg.Here, whether the duration of a period is long or short may bedetermined based on whether or not the duration of the period is longerthan a threshold value. The threshold value is stored in the storageunit 27, for example. Similarly, whether the amount of breath is largeor small may be determined based on whether or not the amount of breathin the period is greater than a threshold value. The threshold valuesmay be fixed, or changed as appropriate according to the tendencies andthe characteristics of the user. It can be seen from the relationshiptable shown in FIG. 9B that the SBP decreases by 4 mmHg per secondduring inhalation, and the SBP decreases by 10 mmHg per liter of breath.Note that tables shown in FIGS. 9A and 9B are examples, and it is alsopreferable that the amount of changes in the DBP and the amount changesin the AI are recorded. It can be said that these relationship tablesare indicators indicating the relationship between breathing and changein blood pressure. The relationship tables thus generated are stored inthe storage unit 27, and used for various kinds of processing that isperformed by the processing unit 51.

Note that, if it is possible to use a past case database in whichrelationship tables are registered, which show the relationship betweenbreathing and changes in blood pressure for a large number of subjects,the indicator extraction unit 50 may acquire, from the past casedatabase, data of another subject who is similar to the user in terms ofthe relationship between breathing and changes in blood pressure, andgenerate a relationship table for the user, considering the data of thesubject as well. Thus, it is possible to generate a more accurate andobjective relationship table.

Next, the following describes an example of processing that is performedby the processing unit 51. For example, the processing unit 51 may reada relationship table stored in the storage unit 27, and outputinformation representing the relationship between the user's breathingand changes in blood pressure, from the output unit 25. At this time,information representing the relationship between the user's breathingand changes in blood pressure may be output in the form of a table asshown in FIGS. 9A and 9B, or in a different form.

Also, the processing unit 51 may perform breathing patternrecommendation processing based on a relationship table. Breathingpattern recommendation processing is performed to suggest a breathingpattern that is to be followed in order to achieve a desired change inblood pressure. For example, it is envisioned that a user experiences anincrease in blood pressure or poor physical condition, and wishes toregulate blood pressure by using a breathing technique. If this is thecase, the user inputs a target value of a change in blood pressure,using the input unit 24 of the biological information analysis system10. For example, it is envisioned that that user has entered a targetvalue to “lower the systolic blood pressure (SBP) by 30 mmHg”. Theprocessing unit 51 refers to relationship tables in the storage unit 27,and designs a breathing pattern (the duration of exhalation, theduration of inhalation, an exhale amount, an inhale amount, the numberof breaths, and so on) that is required to lower the SBP by 30 mmHg. Atthis time, if a plurality of kinds of breathing patterns can beconceived of, the most appropriate breathing pattern is preferablyselected, considering the ease with which the user can follow thepattern.

Thereafter, the processing unit 51 recommends a desirable breathingpattern to the user via the output unit 25. For example, it ispreferable that the processing unit 51 recommends a specific breathingpattern, saying “breathe in for five or more seconds, ten times”, forexample. As a result, the user can control his/her blood pressure, usingan appropriate breathing technique, and prevent a cardiovascular eventfrom occurring.

However, if the user is recommended to “breathe in for five or moreseconds, ten times”, there is the possibility of the user being unableto actually breathe as instructed. Therefore, the processing unit 51 mayprovide a breathing exercise function. For example, in a state where therespiration sensor and the biological information analysis system 10 areworn, the processing unit 51 provides a task, saying “breathe in forfive or more seconds, ten times”, for example, from the output unit 25.While the user is performing the task, the processing unit 51 monitorsbreathing and blood pressure, using the respiration sensor and thebiological information analysis system 10, and evaluates whether or notthe user is successfully breathing and controlling his/her bloodpressure according to the task, and notifies the user of the results ofevaluation via the output unit 25. Using such a function, the user canacquire a breathing technique in an objective manner.

The configurations according to the above-described embodiment andexamples are no more than specific examples of configurations accordingto the present invention, and are not intended to limit the scope of thepresent invention. The present invention may employ various specificconfigurations without departing from the technical idea thereof.

The technical idea disclosed in the present description can be specifiedas the following aspects of the present invention.

Supplementary Note 1

A biological information analysis device comprising:

a hardware processor; and a memory that is configured to store aprogram,

wherein the hardware processor is configured to execute the program to

extract, from time-series data regarding blood pressure waveformsconsecutively measured by a sensor that is configured to be worn on abody part of a user and to be capable of non-invasively measuring ablood pressure waveform for each heartbeat, and from time-series dataregarding breathing measured by a respiration sensor during a period oftime corresponding to the time-series data regarding blood pressurewaveforms, an indicator indicating the relationship between the user'sbreathing and changes in blood pressure, and perform processing that isbased on the indicator thus extracted.

Supplementary Note 2

A biological information analysis system comprising:

a sensor that is configured to be worn on a body part of a user and tobe capable of non-invasively measuring a blood pressure waveform foreach heartbeat; a hardware processor; and a memory that is configured tostore a program,

wherein the hardware processor is configured to execute the program to

extract, from time-series data regarding blood pressure waveformsconsecutively measured by a sensor that is configured to be worn on abody part of a user and to be capable of non-invasively measuring ablood pressure waveform for each heartbeat, and from time-series dataregarding breathing measured by a respiration sensor during a period oftime corresponding to the time-series data regarding blood pressurewaveforms, an indicator indicating the relationship between the user'sbreathing and changes in blood pressure, and

perform processing that is based on the indicator thus extracted.

Supplementary Note 3

A biological information analysis method comprising:

a step of extracting, from time-series data regarding blood pressurewaveforms consecutively measured by a sensor that is configured to beworn on a body part of a user and to be capable of non-invasivelymeasuring a blood pressure waveform for each heartbeat, and fromtime-series data regarding breathing measured by a respiration sensorduring a period of time corresponding to the time-series data regardingblood pressure waveforms, an indicator indicating the relationshipbetween the user's breathing and changes in blood pressure, using atleast one hardware processor; and

a step of performing processing that is based on the indicator thusextracted, using at least one hardware processor.

INDEX TO THE REFERENCE NUMERALS

-   1 . . . biological information analysis device, 2 . . . measurement    unit-   10 . . . biological information analysis system, 11 . . . main body,    12 . . . belt-   20 . . . blood pressure measurement unit, 21 . . . body movement    measurement unit,-   22 . . . environment measurement unit, 23 . . . control unit, 24 . .    . input unit, 25 . . . output unit, 26 . . . communication unit, 27    . . . storage unit, 28 . . . respiration measurement unit-   30 . . . pressure sensor, 31 . . . pressurizing mechanism, 300 . . .    pressure detection element-   50 . . . indicator extraction unit, 51 . . . processing unit

1. A biological information analysis device comprising: an indicatorextraction unit configured to extract, from time-series data regardingblood pressure waveforms consecutively measured by a sensor that isconfigured to be worn on a body part of a user and to be capable ofnon-invasively measuring a blood pressure waveform for each heartbeat,and from time-series data regarding breathing measured by a respirationsensor during a period of time corresponding to the time-series dataregarding blood pressure waveforms, an indicator indicating arelationship between the user's breathing and changes in blood pressure;and a processing unit configured to perform processing that is based onthe indicator thus extracted.
 2. The biological information analysisdevice according to claim 1, wherein the indicator extraction unit isconfigured to specify a plurality of periods of time that have the samebreathing pattern, from the time-series data regarding breathing, andextract an indicator indicating the relationship between breathing andchanges in blood pressure for the breathing pattern, from pieces of dataregarding blood pressure waveforms respectively corresponding to theplurality of periods of time.
 3. The biological information analysisdevice according to claim 2, wherein the indicator extraction unit isconfigured to extract, as the indicator, a tendency in changes in bloodpressure and/or the amount of changes that is/are common to pieces ofdata regarding blood pressure waveforms.
 4. The biological informationanalysis device according to claim 2, wherein the indicator extractionunit is configured to classify ways the user breathes, into a pluralityof breathing patterns, based on the time-series data regarding theuser's breathing.
 5. The biological information analysis deviceaccording to claim 4, wherein the time-series data regarding breathingincludes, for each of a plurality of periods of time that include anexhalation period and an inhalation period, the length of the period oftime and/or the amount of breath, and the indicator extraction unit isconfigured to classify the plurality of periods of time into a pluralityof breathing patterns based on the length of the period of time and/orthe amount of breath.
 6. The biological information analysis deviceaccording to claim 4, wherein the indicator extraction unit isconfigured to extract an indicator indicating the relationship betweenbreathing and changes in blood pressure for each of the plurality ofbreathing patterns.
 7. The biological information analysis deviceaccording to claim 1, wherein the processing unit is configured toperform processing to output information representing the relationshipbetween the user's breathing and changes in blood pressure, based on theindicator.
 8. The biological information analysis device according toclaim 6, wherein the indicator extraction unit is configured togenerate, for each of the plurality of breathing patterns, arelationship table that defines an indicator indicating the relationshipbetween breathing and changes in blood pressure, and the processing unitis configured to select a breathing pattern that is to be followed inorder to achieve a desired change in blood pressure, based on therelationship table, and recommend the selected breathing pattern to theuser.
 9. The biological information analysis device according to claim1, wherein the indicator extraction unit includes, as changes in bloodpressure, at least one of: changes in systolic blood pressure; changesin diastolic blood pressure; changes in an Al (Augmentation Index);changes in the number of times a surge in blood pressure occurs; andchanges in the amount of an increase in a surge in blood pressure.
 10. Abiological information analysis system comprising: a sensor that isconfigured to be worn on a body part of a user and to be capable ofnon-invasively measuring a blood pressure waveform for each heartbeat;and the biological information analysis device according to claim 1, thebiological information analysis device being configured to analyzebiological information, using data regarding blood pressure waveformsconsecutively measured by the sensor.
 11. The biological informationanalysis system according to claim 10, further comprising: a respirationsensor.
 12. A non-transitory computer-readable medium storing a programthat causes a processor to function as the indicator extraction unit andthe processing unit of the biological information analysis deviceaccording to claim
 1. 13. A biological information analysis methodcomprising: a step of extracting, from time-series data regarding bloodpressure waveforms consecutively measured by a sensor that is configuredto be worn on a body part of a user and to be capable of non-invasivelymeasuring a blood pressure waveform for each heartbeat, and fromtime-series data regarding breathing measured by a respiration sensorduring a period of time corresponding to the time-series data regardingblood pressure waveforms, an indicator indicating a relationship betweenthe user's breathing and changes in blood pressure; and a step ofperforming processing that is based on the indicator thus extracted.